1. Field of Invention
The current invention relates generally to apparatus, systems and methods for guiding projectiles. More particularly, the apparatus, systems and methods relate to a tail kit for guiding projectiles. Specifically, the apparatus, systems and methods provide for a tail kit with a thruster that controls the body angle of attack which controls the aerodynamic force or lift of a projectile when guiding the projectile.
2. Description of Related Art
Generally, precision mortar systems are implemented with a guidance kit that is added to the nose of the round. Lift is generated by controlling the body angle of attack. Lifting elements in front of the center of gravity (CG) are used to control the body angle of attack which also generates additive lift. These lifting elements can be thrusters, aerodynamic surfaces such as canards or wings, air diverters that collect air at the nose and push it out the side or thrusters. Generally, guidance systems added to the nose cannot truly be kits as they decouple the fuse from the safe and arm system. Since the fuse and arm system are now separated and part of the guidance package, the guidance system is an integral part of the round and cannot be removed in the field.
One aspect of mortar fire is its use as a suppression round. In this case, a rapid continuous and scattered impact of rounds causes the enemy to take cover. A guided round can actually slow the pace in this type of mission due to its programming requirements where an unguided round with inherent dispersion can be rapidly fired by dropping rounds in fast succession into the tube. Due to the desire of scattered impacts, a guided round in this case is wasted.
Other tail kit approaches have been developed for dropped weapons. A joint direct attack munition (JDAM) is an example that uses such an approach. This system uses large moveable tail surfaces aft of the CG to execute maneuvers. Because the tail has to push on the round in the opposite direction of the desired maneuver in order to hold angle of attack, the lifting surfaces actually subtract lift reducing total maneuver capability.
A tail kit for a mortar guidance solution must survive in a difficult environment. The mortar is launched by igniting a rapid burn propellant charge. This charge creates extreme pressures behind the round within the mortar tube that act to rapidly accelerate the round out of the tube. Any controlled mechanism must survive this environment and any interface between drive systems and wings create an opening through which hot gases and explosive residues can enter.
In order to use the currently fielded launch tubes and barrels, the volume behind the round cannot increase without degrading muzzle velocity and therefore range capability. With these constraints, the volume occupied by the tail must not grow in volume or length. Addition of flip out surfaces to enhance the tail area is complicated by the need to provide a motor or a mechanism driven by a shaft within the current tail volume. The volume required for motors and the mechanism further reduces the available lift generated by the tail. Analysis of the current tail area, disregarding the motor or mechanism, shows insufficient lift to steer the round. Adding flip out features to enhance tail control further aggravates the issues of constrained volumes. Given the extreme environments and constrained volumes, any kind of mechanically controlled rear lifting element is difficult if not impossible for an explosively launched round.
A need exists, therefore, for an improved apparatus, system and method of a more capable device for guiding projectiles.